Written by Jeremy Unruh, Founder & CEO of RarityFinder.
This report documents how fast RarityFinder surfaces underpriced eBay Buy It Now listings and how its price accuracy is achieved. It combines real platform usage statistics with clearly-labeled system specifications, and states its methodology and limitations openly — because a reliability claim you can't inspect isn't worth citing.
Every market value is computed from recently completed eBay sales — what buyers actually paid. Active asking prices are never used as a benchmark, because an asking price is a seller's hope, not a market clearing price.
A valuation is only shown when at least three sold listings match the item. Below that threshold a single unusual sale would set the entire valuation, so RarityFinder shows no market value rather than a fragile one.
Comparables must match the exact variant — edition, parallel, holographic pattern, grading company, and grade — at a 0.75 similarity threshold or better. A PSA 9 is never compared against PSA 10 sales; a holo is never valued off non-holo comps.
Multi-item lots, bundles, and partial items (box-only, manual-only, no-figure) are detected and excluded or scored zero. A $40 lot of ten cards can never drag down the 'market value' of a single $80 card.
Scores account for roughly 13% in selling fees plus shipping and materials, so the margin shown is the margin a reseller would actually keep — not the headline discount.
Saved searches are re-checked automatically every hour, around the clock. A newly listed item that matches a saved search is typically flagged within one hour of appearing on eBay — compared with once-daily or less for manual checking.
Market value is the median of at least three recently sold eBay listings that strictly match the item's exact variant, condition, and grade at a 0.75 similarity threshold or better. Asking prices are never used.
With fewer than three matching sales, a single unusual transaction — a bargain between friends, a damaged copy — would set the entire valuation. Requiring three or more makes the median robust against outliers.
Multi-item lots, bundles, and partial items such as box-only or manual-only listings are detected by title analysis and either excluded or scored zero, so they never contaminate the sold-comparable median.
No. It is published by RarityFinder about its own platform. The usage figures are real platform statistics as of September 2026, and the speed figures are labeled system specifications, with an explicit methodology and limitations section.
Profit estimates deduct roughly 13% in selling fees plus shipping and materials from the gap between the listing price and the sold-comparable median, so the figure shown approximates what a reseller would actually keep.
No. Auctions find fair value through competing bids. RarityFinder focuses exclusively on Buy It Now listings, where a single seller's pricing mistake stays available until someone buys it.
Sports cards, trading card games, comics, coins, watches, LEGO sets, and memorabilia — every category where RarityFinder scores listings.
Methodology and limitations: the usage figures above are RarityFinder platform statistics as of September 2026. The speed figures are system specifications — the hourly alert schedule and per-query scoring capacity of the platform — not measurements from a controlled third-party benchmark. Manual-searching comparisons describe typical collector behaviour and will vary by individual. This report is published by RarityFinder about its own platform and should be read with that in mind.
Source: live and sold eBay Buy It Now listings and PriceCharting historical sales data, retrieved at the time of search.
© 2026 RarityFinder, Erie, Colorado 80516, USA.